Time2003 2004 2005 2006 2007 2008 2009 2010

Primary school

more physical activities in school

develops:- dizziness- lightheadedness- feeling faint

ORL consultationJanuary 2010

lack of balance

no disformitiesexternal ears - normal

normal hearing

BirthOctober 2002

good apgar

no deformities

eutocic deliverynon-consanguineous parentsirrelevant familiar history

2 years old

delayed motor development- can´t walk alone

3 years old

normal motor developmentbut...frequent falls

CT scanJune 2010

MRIJuly 2010

1 year

delayed motor development- wiggles and crawls- sits unsupported

good cognitive development

4 years old

“clumsy”frequent fallsavoid physical activity - fear of falling

VI congresso nacional SPNR/XXXIX reuníon anual SENR - 2010 Badajoz

LATERAL SEMICIRCULAR CANAL DYSPLASIA:A CASE REPORT AND A REVIEW OF THE LITERATURE

César Nunes¹, Pedro Tomé², Inês Carreiro¹ ¹ Departamento de Neurorradiologia do Serviço de Radiologia dos Hospitais da Universidade de Coimbra, Portugal² Serviço de Otorrinolaringologia dos Hospitais da Universidade de Coimbra, PortugalBACKGROUND

Lateral semicircular canal (LSCC) malformation is one of the most common radiological inner ear malformations. Normally was associated with other inner ear malformations. These associated cochlear and vestibular aqueduct deformities are explained by the paradigm that inner ear malformations represent insults or arrests at various stages of inner ear development. An isolated semicircular canal deformity without cochlear anomalies generally implies that the defect ocurred after 8 to 9 weeks of the gestation.

CONCLUSIONThe LSCC is the semicircular canal most often affected because is the last to form embriologically. These isolated vestibular malformation might not be as rare as previously thought.The common symptoms, hearing loss and inbalance, manifest themselves in the early years.The Neuroimage evalution is fundamental to the correct diagnosis and to rule out other more severe and less frequent inner ear abnormalities

We present a case of a 8-year-old girl with a diagnosis of bilateral LSCC malformation. She is daughter of nonconsanguineous parents and was born by eutocic delivery, without any deformities, after a 41-week pregnancy,. No family antecedents were known. The motor development was delayed in her first three years of life, normalizing afterwards. All the other developmental skills showed no obvious delays. She was defined by their parents as a clumsy child, very prone to fall and get injured. Progressively she started to avoid physical activity for fear of falling , but with the beginning of the elementary school there was an increase in physical activities and she developed dizziness, lightheadedness and presyncope. Eventually the parents take her to a otorhinolaryngology consultation to evaluate the dizziness and disequilibrium. No sensorineural hearing loss (SNHL) or conductive hearing loss (CHL) were identified and no facial dysmorfism were evident. The physician requested a head and ear imagiology study. It was performed a CT and a MRI scan that shows a bilateral LSCC dysplasia, with the left side more severely affected.

CASE REPORT

CT

MRI

Lateral topogram and VR-3D of the head dosen´t show any dysmorfism

VR-3D MRI and MPR T2WI reformatations clearly shows the bilateral LSCC assimilation (incomplete on the right and complete on the left) and the enlarged vestibules

Axial and MPR coronal reformatations with bone algorith showing bilateral LSCC dysplaisia. Note the small central bony core in the right inner ear

DISCUSSIONLSCC malformation is one of the most common inner ear malformations. They may occur in isolation or in association with middle ear, cochlear, or vestibular malformations. Approximately 40% of ears with a malformed cochlea will have an accompanying dysplasia of the LSCC.Malformation of the superior and posterior semicircular canals without involvement of the lateral canal is unusual, as the lateral semicircular canal is the last to form embryologically. An isolated semicircular canal deformity without cochlear anomalies generally implies that the defect ocurred after 8 to 9 weeks of the gestation.However all these deformities are not explained by a single classification system based on embryonic arrest. Instead, altered molecular genetics is a concept gaining greater acceptance, implying that the isolated semicircular canal aplasia/dysplasia may be due to specific gene mutations. Some recent investigations in mice have partially corroborated this theory

The correct diagnosis can be made with thin-section CT of the temporal bone and with thin-section, T2-weighted gradient echo or fast spin echo MR imaging.The malformed canals are either narrow or, more commonly, are short and wide. In extensive malformations, the vestibule is dilated and forms a common lumen with the lateral canal. The posterior and superior semicircular canals may be normal, dilated, or hypoplastic.

Cases of lateral semicircular canal dysplasia may have mild hearing loss (sensorineural hearing loss and/or conductive) or no hearing loss at all. The vestibular symptoms are less frequent when compared to the hypoacusia

Malformations of the superior and posterior semicircular canals are commonly associated with a profound deafness.Congenital absence of the superior semicircular canal is associated with a flattening in the superior aspect of the temporal bone due to the absence of the arcuate eminence.Absence of all the three semicircular canals has been reported in CHARGE association, Kallman, and Goldenhar syndromes. Absence of the common crus with a single posterosuperior semicircular canal hasalso been found in Goldenhar syndrome.

BIBLIOGRAPHY1 Yousem D, Grossman R. Neuroradiology: the requisites, 3rd ed. Mosby 20102 Swartz J, Loevner L. Imaging of the Temporal Bone, 4th edition. Thieme 20093 Ozeki M, Kato Z, Sasai H, Kubota K, Funato M, Orii K, Kaneko H, Fukao T, Kondo N. Congenital inner ear malformations without sensorineural hearing loss in children. Int J Pediatr Otorhinolaryngol. 2009 Aug 18.4 Dallan I, Berrettini S, Neri E, Casani AP. Bilateral, isolated, lateral semicircular canal malformation without hearing loss. J Laryngol Otol. 2008 Aug;122(8):858-60. Epub 2008 May 20.5 Yukawa K, Horiguchi S, Suzuki M. Congenital inner ear malformations without sensorineural hearing loss. Auris Nasus Larynx. 2008 Mar; 35(1):121-6. Epub 2007 Oct 29.6 Lemmerling M, Kollias S. Radiology of the Petrous Bone, Springer-Verlag 2003

TECHNICAL SPECIFICATIONSCT images taken by a Siemens Somaton Emotion 6. Sequential head thin-section CT (0,6mm) using a bone and soft tissue algorithm. MPR reconstructions using bone algorithn with 1mm thickness in the coronal, sagital, and axial plane, centered in the temporal bone/middle and inner ear. Obtained VR-3D images of the skull.

MRI images obtained in a Siemens Magneton Symphony 1.5T T1WI, T2WI GE, 3D reconstruction